1. Field of the Invention
The present invention relates to a multifunction operation tool controlling a work apparatus and a transmission that changes a traveling speed, which are provided to a work vehicle, and also relates to an armrest operation device provided with the multifunction operation tool.
2. Description of Related Art
An armrest operation device controlling a work vehicle is disclosed in U.S. Patent Application Publication No. US 2005/0133292 A1. In this armrest operation device, a transmission control lever protruding upward is arranged forward of an arm resting on an armrest, and a traveling speed of the vehicle can be adjusted by gripping the transmission control lever with the fingers of the arm resting on the armrest and performing a swinging operation. Further, a button to upshift the transmission, a button to downshift the transmission, and a button (switch) to shift the transmission into a park position are arranged on a lateral surface of the transmission control lever. Thus, an operator can operate the above-noted button group with the thumb of the hand gripping the transmission control lever. However, the transmission control lever has a shape of an upright cylinder, and because three buttons are aligned vertically on the lateral surface thereof, the operator is made to grip the transmission control lever from a side. Selecting and operating specific buttons in such a state imposes a burden on the operator's hand when continued.
An armrest operation device similar to that disclosed in U.S. Patent Application Publication No. US 2005/0133292 A1 is disclosed in European Patent Application Publication No. EP 2 277 736 A1. In this armrest operation device, a grip operator having a shape of a mouse (such as used as an input device for computers and the like) is arranged forward of the arm resting on the armrest. A surface of the grip operator is formed by combining a plurality of convex surfaces, and an outer surface of the grip operator includes a top surface forming a rest surface to rest a palm and an operation-related lateral surface on which a plurality of button groups are arranged. By performing button operations with the thumb of the hand resting on the rest surface, the transmission can be upshifted/downshifted and the work apparatus can be lifted/lowered. However, in the grip operator, the rest surface and the operation-related lateral surface form one convex surface. Thus, when the palm rests on the rest surface, the thumb naturally comes into contact with the operation-related lateral surface. For this reason, an operator who rests a hand on the rest surface must take care not to press any unnecessary buttons. This imposes a burden on the operator and reduces an advantage of relaxing the hand by resting the hand on the rest surface.